Rapid risk assessment: Review of the epidemiological situation of West Nile virus infection in the European Union

In the ongoing 2011 West Nile virus transmission season, cases have been reported from newly affected geographical areas. This was not entirely unexpected since areas with favourable ecological parameters for the interaction between migratory birds, resident birds, competent mosquito vectors and humans are known to be at risk for the establishment of active and efficient transmission of the virus to humans. Further geographical extension of affected areas is therefore likely in the coming years.
Multi-sectoral collaboration and intensified surveillance made it possible to detect West Nile virus in new areas and identify WNV lineage 1 and lineage 2, which are now both circulating in Europe.
EU Member States are responding to this situation with the implementation of preventive measures, including the safeguarding of blood supplies. However, important gaps remain in our current knowledge of West Nile virus epidemiology, and further research and studies are needed in this context.